1. Field of the Invention
The present invention relates to a circuit device including a heat-generating electronic component and a heat detection component, and to a method of manufacturing the circuit device.
2. Description of the Related Art
As a circuit device including a heat-generating electronic component and a heat detection component, there is generally known a circuit device including a heat-generating electronic component, such as a varistor, a semiconductor device, or a transformer, and a heat detection component, such as a temperature fuse for detecting a change in heat generated by the heat-generating electronic component and protecting it. In the circuit device of the above-mentioned type, the heat-generating electronic component and the heat detection component are arranged in a positional relationship such that the heat detection component is close to the heat-generating electronic component, in order that the heat detection component may quickly detect heat as soon as the heat-generating electronic component generates the heat. Japanese Unexamined Utility Model Registration Application Publication No. 58-193441 discloses one example of a related-art circuit device including a heat-generating electronic component and a heat detection component. In the related-art circuit device, a transistor as the heat-generating electronic component and a temperature fuse as the heat detection component are mounted in a close relation state where the temperature fuse is contacted with a resin molded portion of the transistor. Thus, it is regarded as important to maintain the above-mentioned close positional relationship when the heat-generating electronic component and the heat detection component of the circuit device are mounted.
Meanwhile, in consideration of influences upon environmental loads in recent years, materials having high melting temperatures, such as lead-free solder, have been primarily used for connection of circuit components instead of using leaded solder. Accordingly, when mounting the heat detection component by employing the solder flow technique that requires the heat detection component to be dipped in the solder for a relatively long time, heat is conducted to a heat detection element through lead terminals of the heat detection component, thus resulting in a possibility that characteristics of the heat detection element may degrade, or that the function of the heat detection element may be lost. For that reason, it has been difficult to carry out integral mounting of the heat detection component and the heat-generating electronic component by employing the solder flow technique.
In addition, when the integral mounting of the heat-generating electronic component and the heat detection component is carried out using the solder flow technique, there has been a possibility that the lead terminals of the heat detection component may be bent due to the weight of the heat detection element itself, and that the close positional relationship between the heat-generating electronic component and the heat detection component may no longer be maintained.